I agree with you, the RACQ website is nonsense. Early alternators output about 30 amps, and nowadays 55, 75 or even more is typical. If that won't recharge it, why would a charger? Built-in regulators control the voltage to 13.6-14 volts, giving 2-3 amp trickle charge when fully charged. Modern systems controlled by the engine management computer I think reduce the trickle charge to near zero, saving a little power and perhaps giving better battery life by lower gassing.This is something I've always done when jump starting cars.
When started, I check for 13.5+v across the terminals to be certain the alternator's working.
However, I've had a look at the RACQ website and its advising the following -
After leaving the car's lights on and flattening the battery, going for a drive will recharge it
You won’t fully recharge your battery by going for a drive, idling the engine, or going for a short stop-start trip. In fact, ‘surface’ charging or continuous undercharging will lower the capacity of the battery over time and shorten its life. You could also void the battery warranty by not recharging it correctly.
The only way to reliably restore a flat battery’s charge is to use an appropriate multi-stage battery charger. The charger voltage needs to be high enough to mix the battery acid evenly in the electrolyte to prevent ‘stratification’.
I've never had bother with the alternator charging the battery!